Buffer overflow in Cesanta Mongoose
CVE-2026-5244
A vulnerability has been found in Cesanta Mongoose up to 7.20. This affects the function mg_tls_recv_cert of the file mongoose.c of the component TLS 1.3 Handler. Such manipulation of the argument pubkey leads to heap-based buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. Upgrading to version 7.21 mitigates this issue. The name of the patch is 0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1. It is advisable to upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.
Vulnerability class: Buffer Overflow
EPSS: 0.007 (50.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L.
Affected products
- Cesanta Mongoose — versions 7.0, 7.1, 7.2
Weakness classification (CWE)
References
- cna@vuldb.com (technical-description, VDB Entry, Third Party Advisory, vdb-entry)
- cna@vuldb.com (signature, Permissions Required, permissions-required, VDB Entry)
- cna@vuldb.com (Exploit, VDB Entry, Third Party Advisory, third-party-advisory)
- cna@vuldb.com (Patch, patch)
- cna@vuldb.com (Product, Release Notes, patch)
- cna@vuldb.com (Product, product)
Frequently asked questions
- What is CVE-2026-5244?
- CVE-2026-5244 is a high-severity vulnerability in Cesanta Mongoose, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 7.3/10. Published 2026-04-02.
- How severe is CVE-2026-5244?
- High severity. CVSS v3 base score is 7.3 out of 10.